Embodiments of the present invention relate to a concept for measuring a complexly formed object. Further embodiments of the invention relate to a device and a method for a contactless 3D color detection of plants.
For the assessment and/or phenotyping of plant varieties, i.e. for as complete of a description as possible of the specific properties of certain plants and their different genetic characteristics, the description of the plant architecture in general and in the entire course of development is also necessitated in addition to the description of the biological-chemical properties. The most important features of the plant architecture are the geometric properties of the leaves such as leaf area, orientation/position of the leaves, leaf angle, waviness, surface condition, etc. as well as the overall architecture of the plant. What is also essential for phenotypical characterization of plants is their reaction to the environmental conditions such as dryness, heat or disease, which is mainly characterized by a change in the outer shape of the plant as well as by a change in the color properties of the plant.
In the pharmaceutical industry, specific species of plants are employed for producing medicines or vaccines. In this context, there is a need for a high level of automation of the plant production, i.e. as little intervention by personnel as possible, and consequently fully automatic monitoring of plant growth so as to preclude any disruptions in the production as far as possible, or to detect and eliminate them at an early stage. One important aspect in this quality assurance of plant production comprises monitoring growth of the plants over their growth period as well as the early detection of states of stress or disease of individual specimens or of entire batches so as to be able to remove same from the production process.
The evaluation (assessment) and/or phenotyping of plant varieties with regard to the specific features (rate of growth, leaf area, disease resistance, stress resistance, etc.) so far has mainly been performed by trained personnel, who grade, in accordance with a predefined scheme, the various properties upon regular visual inspections of the plants. The largest range of application presumably is assessment in the open field. Laboratory phenotyping of plants so far has also mainly been based on visual inspection.
Since in the last few years there has been an emergence of a high demand for automatic measurement systems enabling objective and measurable evaluation of plants, individual suppliers have already offered automatic measurement systems. Almost all of said systems are suitable for the laboratory application, the plants to be examined being moved, via a transport system, in the plant pot to the measuring station. Here, detection of the plant is performed by means of a digital 2D camera system while the plant is being rotated on a rotation plate by using one or more cameras from different perspectives, which are subsequently reconstructed to form a 3-dimensional overall geometry. However, such systems are able to 3-dimensionally reconstruct relatively simple plant architectures only since with more complex plants, unambiguous association of pixels with the individual parts of the plants is not possible.
In the art, a portable 3D color measurement system for detecting young beet plants in the field has been developed. Said system is based on the laser light-section method in combination with a 2D color camera. It detects, during a linearly scanning measurement operation, the plants of a test lot, respectively, and provides as a result the leaf area for each plant. During the measuring operation, the system is positioned by persons on top of the test lot to be detected. Thus, it is possible to detect approximately one thousand plants per day.
Furthermore, a laboratory system for the automatic 3D color detection of Arabidopsis plants has been developed in the art. With said system it is possible to detect the Arabidopsis plants and to evaluate the various plants in terms of growth and of resistance to stress (heat, dryness). In this system, the test plants in pots, which are arranged on so-called trays, are detected by means of a linear scan process in that a laser line projector illuminates the entire tray by means of a laser fan beam perpendicularly from above and perpendicularly to the linear movement, while by means of two measuring cameras, which are arranged symmetrically with respect to each other and obliquely in relation to the laser fan beam, and with a color camera, the plants are detected with regard to the 3-dimensional shape and the color image, and are subsequently reconstructed. Due to the relatively simple measuring geometry, i.e. due to the laser light irradiation merely from above, said measuring system is suitable only for detecting plants of little complexity, e.g. of young Arabidopsis plants, which advantageously have a very flat leaf formation, i.e. the leaves are advantageously aligned in parallel with the potting compost.